Merging at the same speed as the other highway traffic will ensure that you don’t create a dangerous situation when you merge, with vehicles approaching very fast. Look in your mirrors and pay attention to the other cars while you’re accelerating. You may need to wait a beat or two before accelerating to full speed if you see a line of cars coming up quickly in the lane into which you’re trying to merge.
Look in the rearview mirror, then at your driver’s side mirror. Glance to see that there is no vehicle in your blind spot (close behind you in the lane that you are merging). Check whether someone has slowed or stopped in the ramp/merge lane in front of you.
If you see a car behind you that seems to be slowing down, the driver is probably trying to “let you in”; accelerate and take the person up on the favor. The same goes if you notice cars moving out of the merge lane to make room for you. If you see a car that seems to be speeding up, let the person pass before trying to merge. Sometimes drivers will wave you in with their hands, too. Never assume others will use the correct speed. It’s up to you to react to what happens.